NorthConnex project: A quick guide to the $3b mega-project

Proposal: In early 2012, the NSW Government received an unsolicited proposal from the project's private sector sponsors; Transurban and the Westlink M7Shareholders, to manage the design, construction, maintenance and operation of NorthConnex. In early January 2015, the Australian and NSW governments gave planning approval, and reached contractual and financial close in late January 2015.

Funding: The $3 billion project, consisting of a construction budget of $2.65 billion in addition to land and project delivery costs, is funded through toll charges with a contribution from the NSW and Federal Governments of up to $412.33 million each, including the use of Hornsby Quarry for spoil management.

Overview: The completed$3 billion NorthConnex project will better link Western Sydney and the Central Coast, creating twin nine-kilometre tunnels under Pennant Hills Road, which is regarded as one of the most congested roads in the country. The tunnel motorway includes interchanges to the north and south to accommodate connections at either end of the project. When complete in 2019, it will allow traffic to bypass up to 21 sets of traffic lights, link Sydney's north to the Orbital network, and enable travel from Newcastle (M1) to Melbourne without a single set of traffic lights.

Major tunneling works: The two main tunnels are each around nine kilometres long. Additional tunnels will be excavated for on and off-ramps at both the northern and southern interchanges. The deepest part of the NorthConnex tunnel would be around 90 metres in order to pass under the NorthWest Rail Link tunnel at Beecroft. Over half the tunnel is more than 60 metres deep – about the height of the Sydney Opera House.

The main tunnels would generally be excavated to be around 14 metres wide, with a height of about eight metres. The tunnel excavation would be carried out using road headers and surface miners. Material would be removed from the tunnel at the nearest construction compound where it would be stockpiled and removed by haulage trucks. Member for Berowra Philip Ruddock said "the southern interchange will be used as a temporary construction compound until project completion with almost 615,000 cubic metres of spoil from tunnelling expected to be removed from the two 30 metre deep tunnel shafts.” Finishing work including tunnel lining, pavement construction and mechanical and electrical fit-out would be undertaken progressively following tunnel excavation.

As the Content editor at plantminer.com.au, Sophia works behind the scenes to keep our blog machine in motion. A student of Law and Business, she's very dependent on coffee and loves any excuse to travel.